Unit 3 · Repeating Pattern Sequence
Ancient Altar Gems — Find the Missing Symbol
Lesson 2 of 2
Harder pattern items hide the rule in a story — you must translate the description into a sequence and see which option continues it correctly.
Rule-based sequence problems sit in the medium band on Selective papers; they reward careful reading and testing each answer against every stated constraint.
You must infer the placement or counting rule from the scenario, build the sequence mentally (or on paper), and pick the option that fits all rules — not just the last step.
Objects are arranged or counted under explicit rules (e.g. how many of each type, what repeats, what is forbidden). You choose the next valid state or total.
Best approach: Write the rule in your own words first. Generate the next one or two terms step by step. Eliminate any option that breaks a stated rule before selecting the survivor.
Question
An explorer finds an ancient altar with four glowing gems: Fire, Frost, Lightning, and Thunder. In front of the altar are four stone pedestals representing the seasons: Spring, Summer, Autumn, and Winter.
Touching a pedestal "toggles" the state of the gems it governs (turning a glowing gem dark, or a dark gem into a glow). Initially, all four gems are dark.
The explorer finds these inscriptions on the wall:
| Clues: |
|---|
| - The Spring pedestal awakens the Fire and Frost gems. |
| - The Summer pedestal affects the Lightning and Thunder gems. |
| - The Autumn pedestal changes the Fire, Frost, and Lightning gems. |
| - The Winter pedestal governs only the Thunder gem. |
Which of the following is a logical certainty regarding the state of the gems?
Select an answer to see the explanation.
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